I had the weirdest experience with my S3 a couple weeks ago. I was at an auto repair place waiting for my truck so I decided to listen to Pandora. Several times, the volume jumped from where I had set it (about 60%) to FULL ON, a few seconds later it would go back to the level I had set. This happened several times, so I switched apps thinking it might be a Pandora issue, but the same thing happened with PocketCast. I was using a pair of apple earbuds (the ones that come with iPods). Bluetooth was off, WiFi on, but not in use (connected via 3G).
I thought the problem might have something to do with the earbuds (being Apple and all ), but it seemed to stop when I left the auto repair place and has not happened since, either with the Apple earbuds or any other headphones. Anyone have any idea what might explain this phenomenon? It seems like it has to be something environmental at that shop, but I can't imagine what.